The present invention relates to magnetic head sliders that, in magnetic disk drives and the like, travel along the surfaces of recording media with a very small flying clearance or come into intermittent contact with the recording medium surfaces. More particularly, the invention is concerned with magnetic head sliders that are not only excellent in shock resistance and in flying characteristics in a disk drive that uses small-diameter disks of 1.8 inches or less, but also suitable for mass production.
Magnetic head sliders are each supported by the flexure installed on a suspension, and fly along the surfaces of magnetic disks with a very small clearance or come into intermittent contact with the magnetic disk surfaces. Data is written and read in this way. A prior art slider 101 is illustrated in FIGS. 11 and 12. The slider 101 has a medium-facing surface (bearing surface) 108, which is constructed of a flying surface 102 (102a, 102b, 102c), a shallow-grooved surface 104 (104a, 104b, 104c) slightly lower than the flying surface 102, and a deep-grooved surface 105 even lower than the shallow-grooved surface 104 provided below the flying surface 102. The flying surface 102 includes one pair of left and right leading flying surfaces 102a and 102b provided at rear portions of the shallow-grooved surface 104, near a leading edge, and a central pad 102c provided at a trailing edge and mounted with a magnetic head 103. The shallow-grooved surface 104 includes a shallow-grooved surface 104a present at a leading edge, shallow-grooved rails 104b on lateral sides, and a central pad shallow-grooved surface 104c on the leading side of the central pad 102c. The deep-grooved surface 105 is surrounded by a shallow-grooved surface 104a present at the leading edge, flying surfaces 102a, 102b on the leading side, and the shallow-grooved rails 104b on the lateral sides. In this configuration, a stepped air-bearing action by the shallow-grooved surface 104a and the flying surfaces 102a, 102b, generates a lifting force to make the slider fly above a magnetic disk, and the deep-grooved surface 105 generates a negative pressure at the same time, whereby appropriate air-bearing rigidity and stable flying are ensured. The slider may measure 1.25 mm in length Lx, 1.0 mm in width Ly, and 0.3 mm in height Lz.
In recent years, magnetic disk drives tend to be enhanced in density and to shift to the smaller magnetic disk drives that use smaller disks and are intended for application to more compact digital equipment. In order to respond to these tendencies, sliders are dimensionally reduced as a method of obtaining effective data areas on disk surfaces. A plan view of a compact slider dimensionally reduced to about 70% of the foregoing slider now commonly used is shown in FIG. 12. Slider 101 measures 0.85 mm in length Lx, 0.7 mm in width Ly, and 0.23 mm in height Lz. Use of the compact slider 101 increases a disk's effective data area by 0.3 mm. This increase is a significant improvement for compact magnetic disk drives having a disk size of 25.4 mm (1″) or 20.3 mm (0.8″).
During conventional slider processing, the bearing surfaces for about 40 such sliders lined up in single file from left to right to be lapped as a set in a bar condition. Then the shapes of the bearing surfaces are formed in a dry process such as ion milling, and the bar is split into individual sliders by chipping. Chipping alleviates stresses, thus resulting in the chipped sections of each bearing surface 108 being locally deformed. Both ends of the bearing surface have a concave-shaped profile, looking as if they would jump out toward a recording medium. Local deformation is observed particularly on both sides of the slider. The local deformation causes fluctuations in flying characteristics, impedes low flying and stable flying, and results in disk damage due to contact during load/unload states. In the conventional processes, therefore, flying surfaces 102a and 102b on the leading side are each provided, at both edges, with a 30-μm-wide shallow-grooved surface 109 and externally thereto, a 30-μm-wide chipping allowance 110 having the same depth as that of a deep-grooved surface 105. Length L2 from an edge of the flying surface to an end of the slider is 60 μm, and length L1 from the edge of the flying surface to the shallow-grooved surface is 30 μm.
As its size is reduced, the compact slider decreases in the area of the bearing surface and thus significantly decreases in lifting force based on air-bearing characteristics. To ensure a balance with respect to the reduced lifting force, the suspension load applied to the slider also needs to be reduced. Since the lifting force based on air-bearing characteristics changes in proportion to disk speed, the above tendency is significant in low-disk-speed 2.5-inch magnetic disk drives and in the drives that use magnetic disks 45.7 mm (1.8″) or less in diameter. The problem of the insufficiency in the lifting force based on air-bearing characteristics does not occur in conventional 3.5-inch magnetic disk drives or in the high-speed types of 2.5-inch magnetic disk drives operating at magnetic disk speeds such as 5400 rpm or 7200 rpm. The problem of a decrease in the lifting force is a new problem that is produced by practical use of magnetic disk drives that use a small disk such as 25.4 mm (1″) or 45.7 mm (1.8″).
A decrease in the lifting force causes several problems. A first problem is that air-bearing rigidity decreases and thus that the flying characteristics of the slider deteriorate. A second problem is that since the suspension load needs to be reduced, the shock resistance of the drive during operation decreases. A third problem is that the sliders operating at both positive and negative pressures have a stabilization region in which negative pressures occur in a negative-pressure area, and a “Bi-Stable” region allowing the slider to take both a high-flying mode in which it generates positive pressures even in the negative-pressure area and flies with a flying height of at least 1 μm, and a low-flying mode in which the slider flies with its intended flying height. In systems of a small suspension load, the slider enters the “Bi-Stable” region, taking the high-flying mode very frequently, and thus disabling read/write operations. A fourth problem is that when the suspension load applied is too small and the slider is too short, if the above-mentioned decrease in flying height is caused by an external disturbance, vibration, or a decrease in atmospheric pressure or if, at a leading edge, the slider comes into contact with the disk during slider loading (hereinafter, the contact is referred to as pitch-down), the slider maintains its attitude and continue to be in contact because the slider is unable to escape from that state. Consequent damage to the contact section of the disk will result in information being lost. In a worst case scenario, a crash may even occur. A fifth problem is that because a decrease in bearing area reduces the lifting force and the negative pressure at the same time, the decrease rate of flying height with respect to a decrease in atmospheric pressure is increased, which results in flying height margins being lost.
Although the above-mentioned problems can be solved by providing the leading-side flying surface with a stepped surface of height “h”, the provision of this stepped surface on the flying surface gives the slider the potential that the lowest flying point on the flying surface exists in two places. More specifically, the two places are the trailing edge of the conventional central flying surface and the trailing edge of the stepped surface mentioned above. To achieve low and stable flying, the lowest flying point must always be set at the air outflow edge of the central flying surface, even for this slider.
An object of the present invention is to provide a magnetic head slider that has a stepped surface on a leading-side flying surface, the slider always having its lowest flying point at the trailing edge of a central flying surface.